Method for processing of high meat content food or feed products

ABSTRACT

Food or feed processing systems ( 10, 96 ) include an extruder ( 14 ) and a downstream processor ( 16, 16   a ), and are operable to process high meat food or feed formulations. The processors ( 16, 16   a ) include an elongated processor barrel ( 38 ) presenting an inner surface ( 44 ) with a central body or tube ( 60 ) within the barrel ( 38 ) and presenting an outer surface ( 62 ). The surfaces ( 38, 62 ) thereby define an elongated annular processing region ( 70 ). The barrel ( 38 ) and tube ( 60 ) are steam heated by means of apparatus ( 52, 66 ). A rotatable processing element ( 72 ) is also located within the region ( 70 ). The element ( 72 ) has a plurality of helical vanes ( 88, 104 ), which scrape the surfaces ( 44, 62 ) to prevent buildup of material on these surfaces.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 14/801,946 filed on Jul. 17,2015, which is incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is broadly concerned with processing systems andmethods for food or feed materials, and particularly food or feedformulations containing high meat contents. The systems include anextruder operable to initially process and heat the formulations, with adownstream processor designed to complete the cooking and formation offinal products. The processor includes an elongated processor barrelpresenting an inner surface, with a central body within the processorbarrel presenting an outer surface, thereby defining an annular regionbetween the inner and outer surfaces. An elongated, rotatable processingelement is located within the region about the central body, and haselongated scraping elements in the form of vanes or ribs. Duringprocessing, extrudates from the upstream extruder are passed through theannular region of the processor while the inner and outer surfaces ofthe processor are heated and the processing element is rotated. Thefinal products from the processor may be collected by gravitation orthrough the use of a die assembly.

Description of the Prior Art

Many human foods or animal feeds are produced using extrusion equipment.For example, the majority of pet and aquatic feeds are extrudedproducts. In general, extrusion equipment and processing parameters arewell known in the art for conventional products, such as standard petfeeds containing quantities of protein, fats, and starch. Moreover, suchextruded feeds can be supplemented with relatively small amounts ofmeats using known equipment and processing techniques.

In recent years, however, there has been a demand for extruded productscontaining relatively high quantities of meat, on the order of 30-40% byweight or greater. For example, many pet owners have expressed a desirefor “humanized” pet foods, which have the appearance of meat and similarproducts normally consumed by humans. Despite these demands,incorporation of these large quantities of meat into extruded productshas proved to be difficult, requiring expensive equipment upgrades andsophisticated processing. In fact, 40% meat levels in extruded pet feedshas heretofore proved to be virtually impossible for any reasonablecost.

There is accordingly an unsatisfied need in the art for improvedprocessing systems and methods allowing the high capacity, relativelylow cost production of food or feed products having high meat contents.

Prior art references include U.S. Pat. Nos. 3,694,227, 3,883,672,4,126,177, 4,272,466, 5,228,775, 5,964,278, 5,074,125, 7,097,345,7,811,617, 7,922,384, and 8,628,815; US Published Application No.2014/0037812; foreign references EP2733453 and RU2409993; and thefollowing non-patent references: “Extrusion Systems: Components”http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1312&context=biosysengfacpub(Accessed Jun. 30, 2015); and “Extrusion Cooking and Related Technique”http://www.wiley-vch.de/books/sample/3527328882_c01.pdf (Accessed Jun.30, 2015).

SUMMARY OF THE INVENTION

The present invention overcomes the problems outlined above, andprovides improved food or feed processing systems, and correspondingmethods, allowing incorporation of very high quantities of meat intosuch products. Generally, in the invention, food or feed materials areserially processed first in an extruder and followed by a novelprocessor. The final products are self-sustaining and have verydesirable appearance and eating qualities.

More specifically, the systems of the invention include an extruderhaving an elongated, tubular barrel presenting an inlet for receivingfood or feed material, and a spaced outlet. At least one elongated,axially rotatable, helically flighted screw is located within thebarrel, and the overall extruder is operable to initially process thematerial and to generate a heated extrudate from the extruder outlet.

The downstream processor includes an elongated, tubular processor barrelpresenting an inner surface, an extrudate inlet, and a final productoutput. An elongated body is located within the processor barrel andpresents an outer surface proximal to the inner surface of the processorbarrel so as to define an annular region between these inner and outersurfaces. A tubular processing element surrounds the central body and issituated within the annular region. A drive assembly is operably coupledwith the processing element in order to rotate it relative to the body,and to scrape material from the inner and outer surfaces. Heatingstructure is provided to heat the inner and outer surfaces of theprocessor barrel and central body, to thereby heat material passingthrough the annular region. A conduit operatively connects the extruderoutlet and the extrudate inlet of the processor.

In preferred forms, the extruder is a twin screw extruder having a pairof elongated, intermeshing, helically flighted screw assemblies withinthe extruder barrel. However, the extruder is not normally provided witha restricted orifice die, and rather is designed to force material fromthe extruder barrel outlet into and through the downstream processor.

Advantageously, the central body of the processor is in the form of anelongated, stationary tube equipped with apparatus for steam heating ofthe tube, and the tubular processor rotates relative to the tube.Similarly, the processor barrel is jacketed to permit steam heating ofthe barrel inner surface.

The preferred processing element has a plurality of helical vanes alongthe length thereof, with corresponding openings between the vanes. Inorder to achieve the best processing of materials passing through theprocessor, and to minimize buildup of materials on the barrel and tubesurfaces, the thickness of the processor element closely correspondswith the radial surface-to-surface distance between the inner surface ofthe barrel and the outer surface of the tube. Sufficient clearance isprovided to allow rotation of the processor element, but with adequatescraping of the adjacent surfaces.

Preferably, the central tube and processing element extend beyond theoutput end of the processor barrel, thereby allowing the final productfrom the processor to gravitate in the form of strips or pieces from theprocessing element. If desired, die structure may be provided at theoutlet of the processor.

In some systems in accordance with the invention, it may be necessary ordesirable to provide a scraped surface heat exchanger upstream of theextruder. This is used where, e.g., frozen or cold meat material is tobe processed in the extruder. The function of the heat exchanger is toelevate the temperature of the cold meat to thereby reduce theprocessing load on the extruder.

The invention also provides a method of processing food or feedmaterials, which generally involves serial passage of materials throughan extruder and a novel processor. The method generally comprises thesteps of directing food or feed materials through an extruder includingan elongated, tubular barrel and at least one elongated, axiallyrotatable, helically flighted screw within the barrel, the extruderoperable to initially heat and process the materials and to generate anextrudate from the outlet. Thereafter, the extrudate is passed into andthrough a processor presenting an annular region between the innersurface of an outer processor barrel, and the outer surface of anelongated body within the processor barrel; a tubular, rotatableprocessor element is situated within the annular region. During suchpassage, the inner surface of the processor barrel and the outer surfaceof the processor central body are heated, and the processor element isrotated relative the central body. The final product output from theprocessor may then be collected by gravitation or through the use of adie assembly.

Heating of the inner and outer surfaces of the processor is most easilyeffected by steam heating of the barrel and central body, the latterpreferably in the form of an elongated, closed-ended tube. In mostcases, the tube is stationary, and the processing element rotatesrelative thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram illustrating the preferred equipmentand process steps in the production of food or feed products inaccordance with the invention;

FIG. 2 is a partially schematic, sectional view illustrating a preferredprocessor in accordance with the invention;

FIG. 3 is a perspective view of the preferred processor illustrated inFIG. 2, shown coupled with the outlet end of a twin screw extruder;

FIG. 4 is a vertical sectional view illustrating the internalconstruction of the processor of FIG. 2;

FIG. 5 is a perspective view depicting another processor in accordancewith the invention, shown coupled to the outlet end of a twin screwextruder;

FIG. 6 is a fragmentary perspective view illustrating the outlet end ofthe processor of FIG. 5, and illustrating in detail the peripheral dieand rotary knife structure;

FIG. 7 is a sectional view illustrating the internal construction of theprocessor of FIG. 5;

FIG. 8 is a vertical sectional view illustrating the internalconstruction of the processor of FIG. 5 and

FIG. 9 is a fragmentary perspective view of the output end of theprocessor illustrated in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment of FIGS.1-4

Turning first to FIG. 1, it will be observed that a system 10 for theprocessing of food or feed materials broadly includes an optionalscraped surface heat exchanger 12, a single or twin screw extruder 14,and a processor 16. The invention in some aspects is designed to providefood or feed materials having relatively high meat contents on the orderof 30% by weight or greater. In such cases, a high meat fraction 18 isdirected into heat exchanger 12 where the temperature of the fraction iselevated. The heated output 20 from exchanger 12 is then fed to extruder14, along with a dry ingredient recipe 22. The heated high meat fraction18 and dry ingredient recipe 22 are co-processed in extruder 14 togenerate an extruder output 24. The latter is fed to processor 16 togenerate a final product 26. In other systems, however, the heatexchanger 12 may not be required, particularly if the startingingredients are essentially ambient temperature or warmer.

The extruder 14 is itself conventional, and includes an elongated,multiple-head tubular barrel 28 (shown fragmentarily in FIGS. 3, 5, and7) having one or more elongated, axially rotatable, helically flightedextrusion screw assemblies 30 therein. The barrel 28 includes an input32 (FIG. 1) and an outlet 34. In the illustrated embodiments, theextruder 14 is a conventional twin-screw extruder of the typecommercialized by Wenger Manufacturing, Inc. of Sabetha, Kans. However,in lieu of a conventional restricted orifice die typically provided atoutlet 34, the extruders 14 of the invention are equipped withfrustoconical transitions 36, which do not provide any appreciabledegree of back-pressure within barrel 28, or flow restriction.

The processor 16 illustrated in FIGS. 1-4, includes an elongated tubularbarrel 38 made up of a plurality of end-to-end interconnected tubularbarrel heads 40, which cooperatively define an elongated, continuouscentral bore 42 presenting an innermost surface 44. Each head 40includes a primary body 46 with an outer shell 48 secured thereto, withthe body 46 configured to present steam passageways 50 allowing heatingof the heads. Appropriate steam manifold structure 52 is operativelycoupled to the heads 40 in order to direct steam into the passageways50, and to collect condensate therefrom. The barrel 38 is equipped withan inlet 54, in the form of an upstanding pipe stub 56. An elongatedconveying conduit 58 is attached between transition 36 and stub 56, asbest seen in FIG. 3.

The barrel 38 also has an elongated, closed-ended tube 60 therein, whichpresents an outer surface 62 in facing relationship to the inner surface44 of the barrel 38. In the depicted embodiment, the tube 60 isstationary, and supported by mounts 63. A central steam pipe 64 extendssubstantially the full length of the tube 60 and has a series of axiallyspaced apart steam flow apertures (not shown) for delivering steam intothe tube 60 in order to heat the outer surface 62 thereof. The tube 64is attached to a steam source 66, and a condensate outlet drain 68 isalso provided. It will be observed that the outer surface 62 of tube 60and the adjacent inner surface 44, cooperatively define an annularregion 70. In the embodiment of FIGS. 1-4, the radial,surface-to-surface dimension of the region 70 is 0.66 inches, or 16.8mm.

The overall processor 16 also includes an elongated, axially rotatable,tubular processing element 72, which is positioned within the region 70and extends throughout the complete length of barrel 38. As bestillustrated in FIG. 2, the element 72 has fore-and-aft connectionsections 74, 76 outboard of the adjacent ends of barrel 38, and eachequipped with a gear 77. Coordinated drive assemblies 78, 80 areoperatively coupled with the connection ends 74, 76, and each includes adrive motor 82 having an output gear 84, with a drive belt 86 trainedabout the gears 84 and 77, as shown. The drive assemblies serve torotate the element 72 relative to tube 60 and barrel 28, and thethickness of the element 72 is such that the relative movement serves toeffectively scrape the surfaces 44 and 62 to prevent buildup of materialthereon. The element 72 also includes a plurality of generally helicallyextending vanes 88 with corresponding helical openings 90 therebetween.The vanes 88 extend from a point adjacent the input end of barrel 38 toa point extending beyond the remote output end of the barrel. The areabetween the butt end of barrel 38 and drive belt 86 effectively definesthe output of processor 16. As will be explained in further detail, asproduct emerges from the annular region 70, it falls under the influenceof gravity into collector 92 and thence to an output belt 94.

Operation

Generally speaking, the operation of system 10 involves initiallyheating a high-meat fraction 18 within heat exchanger 12, with theoutput thereof being directed to the input 32 of extruder 14.Simultaneously, a dry fraction 22 is also fed into the input 32. Thefractions are combined and initially processed in extruder 14, and theextruder output 24 is directed to the input 54 of processor 16. In theprocessor, the extruder output is subjected to heating and disruption,with the creation of thin, fully processed strips or pieces of finalproduct 26, which are collected and further treated as desired.Furthermore, the scraping action of the element 72 serves to clean theadjacent surfaces 44 and 62 to prevent undo material buildup thereon.

In more detail, the high-meat fraction 18 is normally frozen or at leastcold (e.g., 5° C.), and the heat exchanger 12 is used to elevate thetemperature of the fraction within the range of from about 30-50° C. Asmentioned previously, if the incoming high-meat fraction is warm or atambient temperature, the heat exchanger 12 need not be used.

The conditions within extruder 14 are relatively mild, and are designedto combine the fractions 18 and 22 without complete denaturing of theprotein in the meat fraction. Generally, the extruder should be operatedso as to create an output 24 having a temperature of from about 50-75°C. The pressure conditions within the extruder barrel normally rangefrom about 150-250 psig, more preferably from about 180-220 psig. Aswill be appreciated, these extruder conditions can be established byappropriate heating of the extruder barrel via steam input and/or byrotation of th screw(s) 30. Screw rpms normally range from about 50-600,and more preferably from about 100-400. Residence times for thematerials passing through the extruder barrel range from about 3-60seconds, more preferably from about 5-40 seconds.

In the processor 16, the combined extruder output 24 is heated andsubjected to the action of the rotating processing element 72. Normally,the final product output 26 should have a temperature of from about80-110° C., more preferably from about 85-100° C. The element 72 istypically rotated at a rate of from about 15-60 rpm, and more preferablyfrom about 20-40 rpm. In order to achieve the desired degree of cook,steam is normally directed to barrel 38 via the manifold system 52, andsimultaneously is directed through central steam tube 64. Accordingly,the adjacent surfaces 44 and 62 are both heated to effect the desiredcook.

The processing element 72 generally does not produce sufficient pressureor motive force to itself propel the material 24 through barrel 38. Thisis achieved principally because of the extruder 14, which continuallyfeeds output 24 into the processor and moves the material along andthrough the barrel 38.

In one hypothetical example, 200 parts fresh meat at a temperature of 5°C. are fed to the scraped surface heat exchanger 12, which serves toelevate the temperature of the meat fraction to 40° C. This meatfraction is then directed to a Wenger twin screw extruder 14 along with100 parts of a dry materials fraction made up of 54% pea flour and 46%potato starch. These materials are co-processed in the extruder 14 at200 psig in order to achieve an extruded product output temperature of60° C. This extruded product is then delivered to processor 16, whichcompletes the cooking and formation of the extrudate so that finalproduct 26 is at a temperature of 90° C. and is in the form of coherentstrips or pieces of product wherein the protein fraction is essentiallycompletely denatured and the starch fraction is essentially completelygelatinized. The final product is then conventionally dried to a totalmoisture content of approximately 10% by weight. The final productcontains 40% by weight meat, 32% by weight pea flour, and 28% by weightpotato starch, on a dry basis, and 25% by weight protein, 17.6% byweight fat, 45.6% by weight starch/fiber, and 10% by weight water, on awet basis. If desired, further downstream treatment of the final productcan be undertaken, e.g., appropriate sizing of the product orapplication of fat to the outer surfaces

Embodiment of FIGS. 5-9

FIGS. 5-9 illustrate another system 96, which is very similar to thesystem 10. The principal differences in the second embodiment arepresent in the processor 16 a, which has a differently configuredprocessing element 98, along with a peripheral die 100 at the output endof the element 98, and a powered rotatable cutting assembly 102.Inasmuch as many of the components of system 96 are identical with thoseof system 10, like components are numbered identically, and will not befurther described.

Specifically, the radial distance between the outer surface 62 ofcentral tube 60, and the inner surface 44 of bore 42 is 1.82 inches, or46.2 mm. Accordingly, the processing element 98 is of thickerconstruction and has a pair of helical vanes 104 therein, withcorresponding helical openings 106 therebetween. It will be observedthat the pitch lengths of the vanes 104 are considerably smaller ascompared with those of vanes 88.

The processor 16 a has an endmost peripheral die 100 (see FIGS. 6 and9), which is in the form of a solid tubular head 108 having a pluralityof die openings 110 formed therein and extending through the thicknessof the head. The head 108 surrounds the forward or output end ofprocessing element 98, so that the material being processed is forcedradially outwardly through the openings 110.

The cutting assembly 102 includes a tubular, axially rotatable mount112, which surrounds die 100 and is equipped with a driving gear 114. Aseries of circumferentially spaced apart, rearwardly extending knives116 are affixed to the mount 112 and extend over the die openings 110. Adrive 118, including drive belt 120, is coupled with driving gear 114 soas to rotate the knives 116 during operation of the processor.

It will thus be appreciated that as the extrudate emerges from theopenings 110, it is cut by the rotating knives 116. This cut productthen falls by gravity into collector 92, as previously explained.

In general, the operating conditions set forth above for the extruder 14and processor 16 in the embodiment of FIGS. 1-4 are also applicable tothe second embodiment of FIGS. 5-9.

The embodiments of FIGS. 1-4 and 5-9 illustrate presently preferredimplementations of the present invention. However, the invention is notlimited to these embodiments, and a number of equipment or processalterations may be made with out departing from the scope of theinvention. For example, the embodiments make use of a pair ofend-mounted drive assemblies for rotating the processing element 72. Ifdesired, only one end of the element 72 need be driven. Also, the tube60 is stationary in the preferred embodiments. This need not be thecase, so long as there is relative movement between the processingelement 72 and the tube 60. Thus, the tube 60 may be rotated at adifferent rotational speed as compared with the processing element 72,and/or the tube 60 may be rotated in the same direction as the element72, or in the opposite direction. While the radial surface-to-surfacedimensions between the inner and outer surfaces of the processors 16 and16 a have been indicated, such radial distances are more generally rangefrom about 5-75 mm, and more preferably from about 10-50 mm. Smallerdistances are of course advantageous from a heat transfer standpoint,but larger distances, and correspondingly thicker processing elements72, give a greater degree of mixing and agitation of the materials beingprocessed.

In addition, it is not necessary that the processing elements 72 or 98be equipped with helical vanes. That is, vanes or scrapers ofessentially configuration may be used, e.g., relatively thin straightvanes or radially outwardly extending blades could be employed. Thepreferred processor barrels and processing elements, while preferably ofessentially constant diameter, may if desired be tapered, or the barrelsmay be tapered and the elements of constant diameter, or vice versa.

We claim:
 1. A method of processing food or feed materials, comprisingthe steps of: directing said food or feed materials through an extruderincluding an elongated, tubular barrel and at least one elongated,axially rotatable, helically flighted screw within the barrel, saidextruder operable to initially heat and process said materials andgenerate an extrudate; and passing said extrudate into and through aprocessor including an elongated, tubular processor barrel presenting aninner surface, an elongated body within the processor barrel presentingan outer surface, with an annular region between said inner and outersurfaces, and a processing element within said annular region, saidpassing step comprising the steps of moving said extrudate through saidannular region while rotating said processing element relative to saidelongated body with the element scraping said inner and outer surfaces,in order to create a final product from the processor.
 2. The method ofclaim 1, said extruder being a twin screw extruder.
 3. The method ofclaim 1, said elongated body comprising a stationary tube.
 4. The methodof claim 1, including the step of heating said elongated body.
 5. Themethod of claim 1, said processing element having a plurality ofelongated vanes along the length thereof with elongated openings betweensaid vanes.
 6. The method of claim 5, said elongated vanes and openingsbeing helical.
 7. The method of claim 1, including the step of rotatingsaid processing element by rotating the element at spaced locationsalong the length thereof.
 8. The method of claim 1, said processingelement extending beyond the end of said processor barrel, including thestep of recovering said final product gravitating from the processingelement outboard of said processor barrel.
 9. The method of claim 1,including the step of forcing material from the processing elementthrough an extrusion die, and cutting the material from the die.
 10. Themethod of claim 9, said extrusion die being a peripheral die, andincluding the step of forcing material from the processing elementradially outwardly through the peripheral die.
 11. The method of claim 1including the step of initially passing food or feed material through aheat exchanger for initial heating thereof, and then passing materialinto said extruder.
 12. The method of claim 1, including the steps ofoperating said extruder by rotating said at least one screw at apressure of from about 150-250 psig, with rotation of said at least onescrew at a rate of from about 50-600 rpm.
 13. The method of claim 1,including the step of rotating said processing element at a rate of fromabout 5-60 rpm.
 14. The method of claim 1, said extruder operable toheat said materials to a temperature of from about 50-75° C.
 15. Themethod of claim 1, including the step of simultaneously heating saidinner and outer surfaces during rotation of said processing element. 16.The method of claim 7, including the step of rotating said processingelement adjacent the ends thereof.